Quirks & Quarks

Why don't we sneeze when we're asleep?

This week's Quirks question comes from Robbie Currie of Collingwood, Ont., who asks: "Why don't we sneeze while we're asleep?"

The body shuts down many muscular systems during sleep

A man sneezes holding a tissue in Berlin. (Roberto Pfeil/Associated Press)
Listen2:31

Originally published on October 20, 2018.

This week's Quirks question comes from Robbie Currie of Collingwood, Ont., who asks: "Why don't we sneeze while we're asleep?"

Wendy Hall, a professor at the school of nursing at the University of British Columbia, explains part of the answer has to do with the fact that our slowed breathing while sleeping means less particulate material ends up on the mucous membranes of our respiratory system — which tends to be what triggers sneezing. 

Further, in sleep, our body tends to be less responsive to outside stimuli so it takes more stimulation to get a response.

Finally in REM sleep in particular, our voluntary muscles tend to be relaxed so we don't act out our dreams, which again tends to damp down a reaction like a sneeze.